The present invention relates to a method of increasing the engine or exhaust braking power of a four-stroke, reciprocating piston internal combustion engine, whereby in the braking operation, in a first and third stroke air is drawn in via an intake valve, and in a second and fourth stroke the air is compressed and, by partially opening an exhaust valve, is discharged against a butterfly valve-type damper that is disposed in the exhaust pipe or manifold.
It is known to provide a damper in the exhaust manifold for the engine or exhaust braking. Such an exhaust brake operates like an air pump that works against the closed exhaust manifold. It is also known during braking operation to control the gas-changing valves in a two-cycle manner, i.e. the air that is drawn in the first and third strokes is compressed by the piston in the second and fourth strokes. As a result, a greater braking action is achieved than is possible where compression is effected during only one piston stroke.
It also known to keep the exhaust valve open slightly during the compression stroke. However, opening of the exhaust valve can only be effected in or shortly prior to the top dead center position of the piston. In so doing, the final compression pressure is of particular significance.
It is an object of the present invention to increase the final compression pressure, i.e. to increase the energy that is to be applied for the compression.